1. Field of the Invention
The present invention relates to processes for producing and cooling titanium dioxide, and more particularly, to such processes wherein the cooling of the titanium dioxide and gaseous reaction products produced is more efficiently carried out.
2. Description of the Prior Art
In the production of titanium dioxide utilizing the chloride process, heated gaseous titanium tetrachloride and heated oxygen are combined in a tubular reactor at high flow rates. A high temperature oxidation reaction takes place in the reactor whereby particulate solid titanium dioxide and gaseous reaction products are produced. The titanium dioxide and gaseous reaction products are cooled by passing them through a tubular heat exchanger along with a scouring medium for removing deposits from the inside surfaces of the heat exchanger. The scouring medium utilized heretofore has been a particulate solid such as sand, sintered or compressed titanium dioxide, rock salt or the like. In spite of the use of a scouring medium, the solid titanium dioxide and other deposits on the inside surfaces of the tubular heat exchanger have only been partially removed thereby leaving deposits which reduce the heat transfer efficiency of the heat exchanger.
Thus, there are needs for improved processes for producing and cooling titanium dioxide whereby deposits in the heat exchanger utilized are more thoroughly removed and high efficiency cooling takes place.
The present invention provides an improved process for producing and cooling titanium dioxide which meets the needs described above and overcomes the deficiencies of the prior art. The improved process of this invention basically comprises the steps of reacting gaseous titanium tetrachloride and oxygen at a high temperature to produce particulate solid titanium dioxide and gaseous reaction products. The produced particulate solid titanium dioxide and gaseous reaction products are cooled by heat exchange with a cooling medium in a tubular heat exchanger. A scouring medium is injected into the heat exchanger for removing deposits of titanium dioxide and other materials from the inside surfaces of the heat exchanger. In order to increase the removal of the deposits from the surfaces and thereby increase the heat transfer efficiency in the heat exchanger, the scouring medium is caused to follow a spiral path through the heat exchanger. After passing through the heat exchanger, the particulate solid titanium dioxide is separated from the gaseous reaction products.
It is, therefore, a general object of the present invention to provide an improved process for producing and cooling titanium dioxide.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of the preferred embodiments which follows when taken in conjunction with the accompanying drawings.